For what it's worth, I think that the primary information
we need (and the "key" to sort libraries by) is compatibility.

I would really like to be able to browse scheme libraries/URI's
where every level in the hierarchy was an implementation
choice mutually exclusive from all others at that level, so
we wouldn't get, eg, TinyCLOS objects mixed up with Meroon
objects and wouldn't find code that requires exact rationals
in the directory path  below an indication that signifies
code which does not require them. That way if you have an
application that doesn't provide exact rationals (or has a
different object system) you don't wind up wasting time.

So to me a scheme URI would be something like

"scheme://R5RS/TinyCLOS/rationals/foo.scm"

and this woud be a key into a small database that mapped
it to a URL giving a web address where it could be downloaded.

				Bear